Above-ground nuclear weapons tests were mostly this, especially later on. After a point, they weren't testing to see if it worked, or what it could do, they were just blowing stuff up for the sake of blowing stuff up. The higher-ups usually justified it as intimidating the filthy communists/capitalist pigs.
Tsar Bomba being a 50 megaton atomic bomb that the Russians let off during the Cold War... Could have been 100 megatons, but the Russians were concerned about fallout. They only made and detonated the one... Not practical to put on a plane I guess...
Ultimate example: The Big Bang!
Properly described, the Big Bang wasn't really an explosion at all, but more like a balloon swelling up at a steady rate. The phrase "Big Bang" was concocted by an advocate of the rival "steady state" cosmological theory, and was intended to poke fun at the notion that the universe arose from a single point's expansion. But the idea of all creation bursting forth from the mother-of-all-Bangs was so captivating that this trope supplanted the swelling-balloon image in popular culture.
Usually backronymed as 'Blast Levelling Everything Very Effectively'.
Grain elevator dust explosion, triggered by sparks from seized bearing.
The Halifax Explosion earns the distinction of being the most devastating accidental, non-nuclear explosion in history, leveling an entire neighborhood and was powerful enough to generate a deadly tsunami.
The largest deliberate artificial non-nuclear explosions were the "Minor Scale" and "Misty Picture" ordnance tests, conducted by the United States government to gather data and test the resilience of military hardware against the sorts of blast and heat effects that could be caused by nuclear attacks.
In his book Project Orion, George Dyson says of his father who worked on Project Orion, Freeman Dyson, that physicists love explosions. He shares an anecdote about how when he was cooking breakfast on a gas oven, he accidentally turned the gas valve up too high, causing a flash of flame to burst out as his father was entering the room. Freeman's reaction was to say, "Oh good, an explosion!"
The largest artificial non-nuclear explosion in history was created by a Soviet N1 rocket, the launch vehicle for their equivalent of the Apollo Program. During its second launch, a fuel pump ingested a loose bolt and exploded inside the rocket. This set off a chain reaction that caused the rocket's engines to shut down, dropping it back onto the launchpad. The entire vehicle blew up on impact, destroying the launch tower along with it. The Soviets never did get an N1 into orbit.
Watch any documentary about the early days of NASA and you'll probably see a montage of several Vanguard and Atlas rockets blowing up, usually right after they're launched (fortunately, these were unmanned test flights). Reporters jokingly referred to such rockets as "Kaputnik" or "Stayputnik," a play on the Russian satellite Sputnik.